ref: bc1cc79225f0b006dd66d4fd81030d06f83bfca2
dir: /sys/src/cmd/python/Modules/selectmodule.c/
/* select - Module containing unix select(2) call. Under Unix, the file descriptors are small integers. Under Win32, select only exists for sockets, and sockets may have any value except INVALID_SOCKET. Under BeOS, we suffer the same dichotomy as Win32; sockets can be anything >= 0. */ #include "Python.h" #ifdef __APPLE__ /* Perform runtime testing for a broken poll on OSX to make it easier * to use the same binary on multiple releases of the OS. */ #undef HAVE_BROKEN_POLL #endif /* Windows #defines FD_SETSIZE to 64 if FD_SETSIZE isn't already defined. 64 is too small (too many people have bumped into that limit). Here we boost it. Users who want even more than the boosted limit should #define FD_SETSIZE higher before this; e.g., via compiler /D switch. */ #if defined(MS_WINDOWS) && !defined(FD_SETSIZE) #define FD_SETSIZE 512 #endif #if defined(HAVE_POLL_H) #include <poll.h> #elif defined(HAVE_SYS_POLL_H) #include <sys/poll.h> #endif #ifdef __sgi /* This is missing from unistd.h */ extern void bzero(void *, int); #endif #ifdef HAVE_SYS_TYPES_H #include <sys/types.h> #endif #if defined(PYOS_OS2) && !defined(PYCC_GCC) #include <sys/time.h> #include <utils.h> #endif #ifdef MS_WINDOWS # include <winsock.h> #else # define SOCKET int # ifdef __BEOS__ # include <net/socket.h> # elif defined(__VMS) # include <socket.h> # endif #endif static PyObject *SelectError; /* list of Python objects and their file descriptor */ typedef struct { PyObject *obj; /* owned reference */ SOCKET fd; int sentinel; /* -1 == sentinel */ } pylist; static void reap_obj(pylist fd2obj[FD_SETSIZE + 1]) { int i; for (i = 0; i < FD_SETSIZE + 1 && fd2obj[i].sentinel >= 0; i++) { Py_XDECREF(fd2obj[i].obj); fd2obj[i].obj = NULL; } fd2obj[0].sentinel = -1; } /* returns -1 and sets the Python exception if an error occurred, otherwise returns a number >= 0 */ static int seq2set(PyObject *seq, fd_set *set, pylist fd2obj[FD_SETSIZE + 1]) { int i; int max = -1; int index = 0; int len = -1; PyObject* fast_seq = NULL; PyObject* o = NULL; fd2obj[0].obj = (PyObject*)0; /* set list to zero size */ FD_ZERO(set); fast_seq=PySequence_Fast(seq, "arguments 1-3 must be sequences"); if (!fast_seq) return -1; len = PySequence_Fast_GET_SIZE(fast_seq); for (i = 0; i < len; i++) { SOCKET v; /* any intervening fileno() calls could decr this refcnt */ if (!(o = PySequence_Fast_GET_ITEM(fast_seq, i))) return -1; Py_INCREF(o); v = PyObject_AsFileDescriptor( o ); if (v == -1) goto finally; #if defined(_MSC_VER) max = 0; /* not used for Win32 */ #else /* !_MSC_VER */ if (v < 0 || v >= FD_SETSIZE) { PyErr_SetString(PyExc_ValueError, "filedescriptor out of range in select()"); goto finally; } if (v > max) max = v; #endif /* _MSC_VER */ FD_SET(v, set); /* add object and its file descriptor to the list */ if (index >= FD_SETSIZE) { PyErr_SetString(PyExc_ValueError, "too many file descriptors in select()"); goto finally; } fd2obj[index].obj = o; fd2obj[index].fd = v; fd2obj[index].sentinel = 0; fd2obj[++index].sentinel = -1; } Py_DECREF(fast_seq); return max+1; finally: Py_XDECREF(o); Py_DECREF(fast_seq); return -1; } /* returns NULL and sets the Python exception if an error occurred */ static PyObject * set2list(fd_set *set, pylist fd2obj[FD_SETSIZE + 1]) { int i, j, count=0; PyObject *list, *o; SOCKET fd; for (j = 0; fd2obj[j].sentinel >= 0; j++) { if (FD_ISSET(fd2obj[j].fd, set)) count++; } list = PyList_New(count); if (!list) return NULL; i = 0; for (j = 0; fd2obj[j].sentinel >= 0; j++) { fd = fd2obj[j].fd; if (FD_ISSET(fd, set)) { #ifndef _MSC_VER if (fd > FD_SETSIZE) { PyErr_SetString(PyExc_SystemError, "filedescriptor out of range returned in select()"); goto finally; } #endif o = fd2obj[j].obj; fd2obj[j].obj = NULL; /* transfer ownership */ if (PyList_SetItem(list, i, o) < 0) goto finally; i++; } } return list; finally: Py_DECREF(list); return NULL; } #undef SELECT_USES_HEAP #if FD_SETSIZE > 1024 #define SELECT_USES_HEAP #endif /* FD_SETSIZE > 1024 */ static PyObject * select_select(PyObject *self, PyObject *args) { #ifdef SELECT_USES_HEAP pylist *rfd2obj, *wfd2obj, *efd2obj; #else /* !SELECT_USES_HEAP */ /* XXX: All this should probably be implemented as follows: * - find the highest descriptor we're interested in * - add one * - that's the size * See: Stevens, APitUE, $12.5.1 */ pylist rfd2obj[FD_SETSIZE + 1]; pylist wfd2obj[FD_SETSIZE + 1]; pylist efd2obj[FD_SETSIZE + 1]; #endif /* SELECT_USES_HEAP */ PyObject *ifdlist, *ofdlist, *efdlist; PyObject *ret = NULL; PyObject *tout = Py_None; fd_set ifdset, ofdset, efdset; double timeout; struct timeval tv, *tvp; long seconds; int imax, omax, emax, max; int n; /* convert arguments */ if (!PyArg_UnpackTuple(args, "select", 3, 4, &ifdlist, &ofdlist, &efdlist, &tout)) return NULL; if (tout == Py_None) tvp = (struct timeval *)0; else if (!PyNumber_Check(tout)) { PyErr_SetString(PyExc_TypeError, "timeout must be a float or None"); return NULL; } else { timeout = PyFloat_AsDouble(tout); if (timeout == -1 && PyErr_Occurred()) return NULL; if (timeout > (double)LONG_MAX) { PyErr_SetString(PyExc_OverflowError, "timeout period too long"); return NULL; } seconds = (long)timeout; timeout = timeout - (double)seconds; tv.tv_sec = seconds; tv.tv_usec = (long)(timeout*1000000.0); tvp = &tv; } #ifdef SELECT_USES_HEAP /* Allocate memory for the lists */ rfd2obj = PyMem_NEW(pylist, FD_SETSIZE + 1); wfd2obj = PyMem_NEW(pylist, FD_SETSIZE + 1); efd2obj = PyMem_NEW(pylist, FD_SETSIZE + 1); if (rfd2obj == NULL || wfd2obj == NULL || efd2obj == NULL) { if (rfd2obj) PyMem_DEL(rfd2obj); if (wfd2obj) PyMem_DEL(wfd2obj); if (efd2obj) PyMem_DEL(efd2obj); return PyErr_NoMemory(); } #endif /* SELECT_USES_HEAP */ /* Convert sequences to fd_sets, and get maximum fd number * propagates the Python exception set in seq2set() */ rfd2obj[0].sentinel = -1; wfd2obj[0].sentinel = -1; efd2obj[0].sentinel = -1; if ((imax=seq2set(ifdlist, &ifdset, rfd2obj)) < 0) goto finally; if ((omax=seq2set(ofdlist, &ofdset, wfd2obj)) < 0) goto finally; if ((emax=seq2set(efdlist, &efdset, efd2obj)) < 0) goto finally; max = imax; if (omax > max) max = omax; if (emax > max) max = emax; Py_BEGIN_ALLOW_THREADS n = select(max, &ifdset, &ofdset, &efdset, tvp); Py_END_ALLOW_THREADS #ifdef MS_WINDOWS if (n == SOCKET_ERROR) { PyErr_SetExcFromWindowsErr(SelectError, WSAGetLastError()); } #else if (n < 0) { PyErr_SetFromErrno(SelectError); } #endif else if (n == 0) { /* optimization */ ifdlist = PyList_New(0); if (ifdlist) { ret = PyTuple_Pack(3, ifdlist, ifdlist, ifdlist); Py_DECREF(ifdlist); } } else { /* any of these three calls can raise an exception. it's more convenient to test for this after all three calls... but is that acceptable? */ ifdlist = set2list(&ifdset, rfd2obj); ofdlist = set2list(&ofdset, wfd2obj); efdlist = set2list(&efdset, efd2obj); if (PyErr_Occurred()) ret = NULL; else ret = PyTuple_Pack(3, ifdlist, ofdlist, efdlist); Py_DECREF(ifdlist); Py_DECREF(ofdlist); Py_DECREF(efdlist); } finally: reap_obj(rfd2obj); reap_obj(wfd2obj); reap_obj(efd2obj); #ifdef SELECT_USES_HEAP PyMem_DEL(rfd2obj); PyMem_DEL(wfd2obj); PyMem_DEL(efd2obj); #endif /* SELECT_USES_HEAP */ return ret; } #if defined(HAVE_POLL) && !defined(HAVE_BROKEN_POLL) /* * poll() support */ typedef struct { PyObject_HEAD PyObject *dict; int ufd_uptodate; int ufd_len; struct pollfd *ufds; } pollObject; static PyTypeObject poll_Type; /* Update the malloc'ed array of pollfds to match the dictionary contained within a pollObject. Return 1 on success, 0 on an error. */ static int update_ufd_array(pollObject *self) { Py_ssize_t i, pos; PyObject *key, *value; self->ufd_len = PyDict_Size(self->dict); PyMem_Resize(self->ufds, struct pollfd, self->ufd_len); if (self->ufds == NULL) { PyErr_NoMemory(); return 0; } i = pos = 0; while (PyDict_Next(self->dict, &pos, &key, &value)) { self->ufds[i].fd = PyInt_AsLong(key); self->ufds[i].events = (short)PyInt_AsLong(value); i++; } self->ufd_uptodate = 1; return 1; } PyDoc_STRVAR(poll_register_doc, "register(fd [, eventmask] ) -> None\n\n\ Register a file descriptor with the polling object.\n\ fd -- either an integer, or an object with a fileno() method returning an\n\ int.\n\ events -- an optional bitmask describing the type of events to check for"); static PyObject * poll_register(pollObject *self, PyObject *args) { PyObject *o, *key, *value; int fd, events = POLLIN | POLLPRI | POLLOUT; int err; if (!PyArg_ParseTuple(args, "O|i:register", &o, &events)) { return NULL; } fd = PyObject_AsFileDescriptor(o); if (fd == -1) return NULL; /* Add entry to the internal dictionary: the key is the file descriptor, and the value is the event mask. */ key = PyInt_FromLong(fd); if (key == NULL) return NULL; value = PyInt_FromLong(events); if (value == NULL) { Py_DECREF(key); return NULL; } err = PyDict_SetItem(self->dict, key, value); Py_DECREF(key); Py_DECREF(value); if (err < 0) return NULL; self->ufd_uptodate = 0; Py_INCREF(Py_None); return Py_None; } PyDoc_STRVAR(poll_unregister_doc, "unregister(fd) -> None\n\n\ Remove a file descriptor being tracked by the polling object."); static PyObject * poll_unregister(pollObject *self, PyObject *o) { PyObject *key; int fd; fd = PyObject_AsFileDescriptor( o ); if (fd == -1) return NULL; /* Check whether the fd is already in the array */ key = PyInt_FromLong(fd); if (key == NULL) return NULL; if (PyDict_DelItem(self->dict, key) == -1) { Py_DECREF(key); /* This will simply raise the KeyError set by PyDict_DelItem if the file descriptor isn't registered. */ return NULL; } Py_DECREF(key); self->ufd_uptodate = 0; Py_INCREF(Py_None); return Py_None; } PyDoc_STRVAR(poll_poll_doc, "poll( [timeout] ) -> list of (fd, event) 2-tuples\n\n\ Polls the set of registered file descriptors, returning a list containing \n\ any descriptors that have events or errors to report."); static PyObject * poll_poll(pollObject *self, PyObject *args) { PyObject *result_list = NULL, *tout = NULL; int timeout = 0, poll_result, i, j; PyObject *value = NULL, *num = NULL; if (!PyArg_UnpackTuple(args, "poll", 0, 1, &tout)) { return NULL; } /* Check values for timeout */ if (tout == NULL || tout == Py_None) timeout = -1; else if (!PyNumber_Check(tout)) { PyErr_SetString(PyExc_TypeError, "timeout must be an integer or None"); return NULL; } else { tout = PyNumber_Int(tout); if (!tout) return NULL; timeout = PyInt_AsLong(tout); Py_DECREF(tout); if (timeout == -1 && PyErr_Occurred()) return NULL; } /* Ensure the ufd array is up to date */ if (!self->ufd_uptodate) if (update_ufd_array(self) == 0) return NULL; /* call poll() */ Py_BEGIN_ALLOW_THREADS; poll_result = poll(self->ufds, self->ufd_len, timeout); Py_END_ALLOW_THREADS; if (poll_result < 0) { PyErr_SetFromErrno(SelectError); return NULL; } /* build the result list */ result_list = PyList_New(poll_result); if (!result_list) return NULL; else { for (i = 0, j = 0; j < poll_result; j++) { /* skip to the next fired descriptor */ while (!self->ufds[i].revents) { i++; } /* if we hit a NULL return, set value to NULL and break out of loop; code at end will clean up result_list */ value = PyTuple_New(2); if (value == NULL) goto error; num = PyInt_FromLong(self->ufds[i].fd); if (num == NULL) { Py_DECREF(value); goto error; } PyTuple_SET_ITEM(value, 0, num); /* The &0xffff is a workaround for AIX. 'revents' is a 16-bit short, and IBM assigned POLLNVAL to be 0x8000, so the conversion to int results in a negative number. See SF bug #923315. */ num = PyInt_FromLong(self->ufds[i].revents & 0xffff); if (num == NULL) { Py_DECREF(value); goto error; } PyTuple_SET_ITEM(value, 1, num); if ((PyList_SetItem(result_list, j, value)) == -1) { Py_DECREF(value); goto error; } i++; } } return result_list; error: Py_DECREF(result_list); return NULL; } static PyMethodDef poll_methods[] = { {"register", (PyCFunction)poll_register, METH_VARARGS, poll_register_doc}, {"unregister", (PyCFunction)poll_unregister, METH_O, poll_unregister_doc}, {"poll", (PyCFunction)poll_poll, METH_VARARGS, poll_poll_doc}, {NULL, NULL} /* sentinel */ }; static pollObject * newPollObject(void) { pollObject *self; self = PyObject_New(pollObject, &poll_Type); if (self == NULL) return NULL; /* ufd_uptodate is a Boolean, denoting whether the array pointed to by ufds matches the contents of the dictionary. */ self->ufd_uptodate = 0; self->ufds = NULL; self->dict = PyDict_New(); if (self->dict == NULL) { Py_DECREF(self); return NULL; } return self; } static void poll_dealloc(pollObject *self) { if (self->ufds != NULL) PyMem_DEL(self->ufds); Py_XDECREF(self->dict); PyObject_Del(self); } static PyObject * poll_getattr(pollObject *self, char *name) { return Py_FindMethod(poll_methods, (PyObject *)self, name); } static PyTypeObject poll_Type = { /* The ob_type field must be initialized in the module init function * to be portable to Windows without using C++. */ PyObject_HEAD_INIT(NULL) 0, /*ob_size*/ "select.poll", /*tp_name*/ sizeof(pollObject), /*tp_basicsize*/ 0, /*tp_itemsize*/ /* methods */ (destructor)poll_dealloc, /*tp_dealloc*/ 0, /*tp_print*/ (getattrfunc)poll_getattr, /*tp_getattr*/ 0, /*tp_setattr*/ 0, /*tp_compare*/ 0, /*tp_repr*/ 0, /*tp_as_number*/ 0, /*tp_as_sequence*/ 0, /*tp_as_mapping*/ 0, /*tp_hash*/ }; PyDoc_STRVAR(poll_doc, "Returns a polling object, which supports registering and\n\ unregistering file descriptors, and then polling them for I/O events."); static PyObject * select_poll(PyObject *self, PyObject *unused) { return (PyObject *)newPollObject(); } #ifdef __APPLE__ /* * On some systems poll() sets errno on invalid file descriptors. We test * for this at runtime because this bug may be fixed or introduced between * OS releases. */ static int select_have_broken_poll(void) { int poll_test; int filedes[2]; struct pollfd poll_struct = { 0, POLLIN|POLLPRI|POLLOUT, 0 }; /* Create a file descriptor to make invalid */ if (pipe(filedes) < 0) { return 1; } poll_struct.fd = filedes[0]; close(filedes[0]); close(filedes[1]); poll_test = poll(&poll_struct, 1, 0); if (poll_test < 0) { return 1; } else if (poll_test == 0 && poll_struct.revents != POLLNVAL) { return 1; } return 0; } #endif /* __APPLE__ */ #endif /* HAVE_POLL */ PyDoc_STRVAR(select_doc, "select(rlist, wlist, xlist[, timeout]) -> (rlist, wlist, xlist)\n\ \n\ Wait until one or more file descriptors are ready for some kind of I/O.\n\ The first three arguments are sequences of file descriptors to be waited for:\n\ rlist -- wait until ready for reading\n\ wlist -- wait until ready for writing\n\ xlist -- wait for an ``exceptional condition''\n\ If only one kind of condition is required, pass [] for the other lists.\n\ A file descriptor is either a socket or file object, or a small integer\n\ gotten from a fileno() method call on one of those.\n\ \n\ The optional 4th argument specifies a timeout in seconds; it may be\n\ a floating point number to specify fractions of seconds. If it is absent\n\ or None, the call will never time out.\n\ \n\ The return value is a tuple of three lists corresponding to the first three\n\ arguments; each contains the subset of the corresponding file descriptors\n\ that are ready.\n\ \n\ *** IMPORTANT NOTICE ***\n\ On Windows and OpenVMS, only sockets are supported; on Unix, all file descriptors."); static PyMethodDef select_methods[] = { {"select", select_select, METH_VARARGS, select_doc}, #if defined(HAVE_POLL) {"poll", select_poll, METH_NOARGS, poll_doc}, #endif /* HAVE_POLL */ {0, 0}, /* sentinel */ }; PyDoc_STRVAR(module_doc, "This module supports asynchronous I/O on multiple file descriptors.\n\ \n\ *** IMPORTANT NOTICE ***\n\ On Windows and OpenVMS, only sockets are supported; on Unix, all file descriptors."); PyMODINIT_FUNC initselect(void) { PyObject *m; m = Py_InitModule3("select", select_methods, module_doc); if (m == NULL) return; SelectError = PyErr_NewException("select.error", NULL, NULL); Py_INCREF(SelectError); PyModule_AddObject(m, "error", SelectError); #if defined(HAVE_POLL) #ifdef __APPLE__ if (select_have_broken_poll()) { if (PyObject_DelAttrString(m, "poll") == -1) { PyErr_Clear(); } } else { #else { #endif poll_Type.ob_type = &PyType_Type; PyModule_AddIntConstant(m, "POLLIN", POLLIN); PyModule_AddIntConstant(m, "POLLPRI", POLLPRI); PyModule_AddIntConstant(m, "POLLOUT", POLLOUT); PyModule_AddIntConstant(m, "POLLERR", POLLERR); PyModule_AddIntConstant(m, "POLLHUP", POLLHUP); PyModule_AddIntConstant(m, "POLLNVAL", POLLNVAL); #ifdef POLLRDNORM PyModule_AddIntConstant(m, "POLLRDNORM", POLLRDNORM); #endif #ifdef POLLRDBAND PyModule_AddIntConstant(m, "POLLRDBAND", POLLRDBAND); #endif #ifdef POLLWRNORM PyModule_AddIntConstant(m, "POLLWRNORM", POLLWRNORM); #endif #ifdef POLLWRBAND PyModule_AddIntConstant(m, "POLLWRBAND", POLLWRBAND); #endif #ifdef POLLMSG PyModule_AddIntConstant(m, "POLLMSG", POLLMSG); #endif } #endif /* HAVE_POLL */ }